The spectral shapes of the 2 micron, 2\nu1 + \nu3
atmospheric CO2 absorption bands, and nearby contributing
hot bands and isotopic bands are all sensitive to
temperatures in the lower atmosphere of Mars ( P > ~1
mbar), via the rotational line intensities. This property
allows tropospheric temperatures to be probed by
ground-based spectral mapping techniques at moderate
spectral resolving power. Telescopic measurements over a
full hemisphere thus show diurnal temperature changes and
atmospheric temperatures near the polar regions, neither of
which can be easily measured by Mars orbiting thermal
spectrometers.

We describe K-band observations of Mars acquired on July 29
and Sept. 20, 2003 (Ls = 231 and 264), as part of an
IRTF/SpeX observing campaign which bracketed the historic
2003 Mars opposition. Long slit grating spectra acquired at
moderately high spatial resolution (80 to 130 km, sub-Earth)
and spectral resolution (R= 1200 to 1500), were transformed
to spatial-spectral (x, y, wavelength) image cubes following
the method described by Glenar et al. (Icarus, 2003).
Atmospheric temperatures are retrieved from the measurements
by fitting to a multi parameter grid of
surface-plus-atmosphere spectral reflectance models which
incorporate gas parameters, simple representations for
surface reflectance shape and dust opacity which is
constrained by concurrent TES measurements. The retrievals
are consistent with TES temperature measurements and allow
extrapolation to polar latitudes as well as a range of local
times.

Funding for this work is provided by the NASA Planetary
Astronomy Program.